The present invention relates to a hybrid integrated circuit and a method for its manufacturing, and in particular, relates to a hybrid integrated circuit for high output power for the use in the microwave band.
A conventional method for manufacuring a hybrid integrated circuit consists of forming patterns on a ceramic substrate either by the thick film circuit process using paste and screen printing, or by the thin film circuit process using the evaporation and photolithography process. Active electronic components like transistors and/or diodes and passive electronic components like inductors, condensors and/or resistors are mounted on the pattern. Wiring among electronic components on the pattern is accomplished through a bonding process and/or soldering process. Also, a lead frame is provided around the pattern for the connections between the hybrid integrated circuit and external circuits. This lead frame provides generally an input signal terminal, an output signal terminal, a power supply terminal, and/or a ground terminal.
However, when it is intended to manufacture a compact hybrid integrated circuit capable of carrying more than several amperes of electric current, there is a difficulty in producing a choke coil in a power source circuit for providing the driving current of transistors. In order to make a choke coil with a large current carrying capacity by the pattern of the ceramic substrate, it has been necessary to make the pattern width large or to make the metallic layer thick. Both such approaches have drawbacks. The use of wide patterns results in an enlarged size of a hybrid integrated circuit, while the use of the thick metallic layer results in a producing cost increase since that layer is usually made of gold.